JP2007074640A - Mobile identification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact mobile identification device called handy type comprising a power-saved interrogator. <P>SOLUTION: When changing the distance between an interrogator and a transponder, one system is deleted between circuits of a mixer and a receiving section requiring two systems for diversity by using phase diversity capable of preventing a demodulation signal output of synchronous detection from being reduced by a phase change in a reception input signal of the interrogator 31. A reception signal to be input to the mixer 10 of the remaining system is caused to have a phase difference of 90° by a distributor 7 and a phase shifter 8, and the reception signal having the phase difference is selected by a switch 9 and input to the mixer 10 or a local signal to be input to the mixer 10 of the remaining one system is distributed to a signal of phase difference 90°, selected by the switch 9 and input to the mixer 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mobile object identification device that performs wireless communication with a mobile information communication body, and more particularly, to a mobile object identification device that uses an IC tag having an IC chip and an antenna and a reader / writer.

  2. Description of the Related Art A mobile object identification device using a radio frequency band, an IC tag having an IC chip and an antenna, and a reader / writer, and a system using the same have been put into practical use in various fields such as distribution, transportation, and medicine.

  There are various types of systems using such IC tags, and different specifications are required for each. For example, when an IC tag (responder) is installed on a product to be transported on a conveyor, and data is written to the IC tag or read using an antenna of a reader / writer (interrogator) fixed on the conveyor side Requires a reader / writer that is stationary and capable of mounting a plurality of antennas. In addition, when data is written to or read from an IC tag attached to an article placed on a warehouse or a shelf, an operator who uses the reader / writer while carrying it is assumed. A reader / writer is required. Note that a portable reader / writer must be reduced in size and power consumption.

  FIG. 3 is a block diagram showing a configuration example of a conventional mobile unit identification apparatus. The interrogator 32 modulates the carrier wave produced by the synthesizer 1 with the modulator 3 based on the data signal sent from the control unit 2, amplifies it with the transmission amplifier 4, and sends it through the circulator 5 and the antenna 6. The responder 20 receives a radio wave from the antenna 21 and transmits a response signal of response data from the antenna 21. The radio wave of the response signal is received by the antenna 6 of the interrogator 32, the received wave is separated from the transmission wave by the circulator 5, and the power is distributed in the same phase by the distributor 7a. One of these power-distributed received waves passes directly to the mixer 10a and the other passes through the phase shifter 8 and is input to the mixer 10b with a phase difference of 90 °.

  The local signal (LO signal) input to the mixer 10a and the mixer 10b uses the carrier wave amplified by the transmission amplifier 4, is distributed by the distributor 7b, and is input to the local signal (LO signal) input terminal of the mixer 10a and mixer 10b. Are input in the same phase. Therefore, the mixer 10a and the mixer 10b perform synchronous detection by mixing received waves with carrier waves. The outputs of the mixer 10a and the mixer 10b are extracted to the baseband signal by the receiving unit 11a and the receiving unit 11b, respectively, and response data is acquired and synthesized, and then sent to the control unit 2. As described above, the interrogator 32 of the conventional example realizes phase diversity for the received signal by distributing the received signal to signals having a phase difference of 90 ° and detecting the received signal.

  Although not shown in the conventional example, the received signal is distributed in the same phase, and the local oscillation signal used as the LO signal is provided with a phase difference of 90 ° using the same configuration as the distributor 7 a and the phase shifter 8. In this way, the phase diversity effect can be obtained as in the conventional example. Here, the means for providing the phase difference may be realized not by the phase shifter 8 but by means such as means for changing the length of the transmission path or means such as using a 90 ° hybrid coupler for the distributor 7a.

  As described above, when the distance between the interrogator 32 and the responder 20 changes, a phase diversity circuit is configured to reduce the demodulated signal output of the synchronous detection due to the phase change of the received input signal of the interrogator 32. Therefore, good sensitivity can be obtained regardless of a change in the distance between the interrogator 32 and the responder 20.

  In addition, a mobile object identification device that improves the deterioration of response wave demodulation efficiency due to a phase is disclosed in Patent Document 1, and a mobile object identification device that aims to expand the communicable distance and reduce the power of the interrogator is disclosed in Patent Document 2. Is disclosed.

JP-A-6-331735 JP 2001-94463 A

  However, these mobile object identification devices have a wide variety of uses, and a compact, power-saving interrogator called a handy type is strongly required. The configuration of the interrogator of the conventional example has a problem in that there are many circuit components, the mounting area is increased, and the power consumption is also increased.

  In Patent Document 1, two output signals of an orthogonal demodulator are added and subtracted by an adder and a subtracter, respectively, thereby obtaining a demodulated signal having a double output compared to the demodulated signal of the conventional example. By operating the selection circuit only at the break of data or the middle part of the bit, it prevents the erroneous transmission of data, and it is a handy type mobile device that strongly requires a power-saving interrogator There was a problem that it was not suitable for the identification device.

  In Patent Document 2, by making the carrier wave output from the interrogator large, the communication distance between the interrogator and the responder can be greatly expanded. By intermittently transmitting from the interrogator, This greatly saves the transmission power of the carrier wave, and there is a problem that it is not well suited to a mobile object identification device that requires a small handy interrogator.

  The present invention has been made to solve the above-described problems, and a technical problem thereof is to provide a mobile object identification device including a handy-type small-sized and power-saving interrogator.

  According to a first aspect of the present invention, there is provided an interrogator for detecting a received signal by a synchronous detection method, receiving an interrogation wave from the interrogator, performing specific modulation on the interrogation wave, and responding. In the moving body identification device comprising a transponder that transmits as a wave, the interrogator is either one of means for giving the received signal a 90 ° phase difference and two signals having the phase difference between each other. Is a mobile object identification device that realizes phase diversity by switching the switch to switch the phase of the received signal.

  According to a second aspect of the invention for achieving the above object, a received signal is detected by a synchronous detection method, an interrogator including a mixer for demodulating the received signal, and an interrogated wave from the interrogator are received. In a mobile unit identification apparatus comprising a transponder that performs specific modulation on an interrogation wave and transmits it as a response wave, means for giving a 90 ° phase difference to the local signal (LO signal) of the mixer and each other A mobile unit that includes a switch for selecting one of two local signals (LO signal) having the phase difference between them, and switches the local signal (LO signal) by switching the switch to realize phase diversity. Device.

  According to the present invention, when the distance between the interrogator and the transponder changes, phase diversity that can prevent a decrease in synchronous detection demodulated signal output due to a phase change of the received input signal of the interrogator is used. One of the mixer and receiver circuits is deleted, and the received signal input to the remaining mixer is given a phase difference of 90 ° by a distributor, phase shifter, etc. Is selected with a switch and input to the mixer, or the local signal input to the remaining one mixer is distributed to signals with a phase difference of 90 °, and then selected with the switch and input to the mixer. By reducing the number of parts and reducing the circuit scale without deteriorating the communication characteristics between the interrogator and the responder used in the mobile object identification device, the handy type is compact and power-saving. Equipped with an interrogator It is possible to provide a moving body identification device.

  A mobile object identification device according to the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration example 1 of an interrogator of a mobile object identification device according to the best mode for carrying out the present invention. FIG. 2 is a block diagram showing a configuration example 2 of the interrogator of the mobile object identification device according to the best mode for carrying out the present invention.

  As shown in FIG. 1, an interrogator 30 (configuration example 1) of a mobile unit identification apparatus according to the best mode for carrying out the present invention includes a synthesizer 1, a control unit 2, a modulator 3, a transmission amplifier 4, and a circulator. 5, a transmission / reception antenna 6, a distributor 7 for distributing received signal power, a phase shifter 8 for shifting the phase by 90 °, a switch 9 for switching the received signal, a mixer 10, and a receiving unit 11. The responder 20 communicates with the interrogator 30 via the antenna 21.

  The interrogation operation of the interrogator 30 (configuration example 1) of the mobile object identification device according to the best mode for carrying out the present invention is as follows. As shown in FIG. 1, the carrier wave signal generated by the synthesizer 1 becomes a modulated signal corresponding to the data signal sent from the control unit 2 by the modulator 3. This modulated signal is amplified by the transmission amplifier 4, passes through the circulator 5 and the antenna 6, and is radiated to the space. The modulated signal radiated to the space is received by the antenna 21 of the responder 20, subjected to predetermined processing by the responder 20, and the response signal is transmitted from the antenna 21.

  The interrogator 30 of the configuration example 1 receives the response signal from the responder 20 by the antenna 6, passes through the circulator 5, and is distributed by the distributor 7. One of the response signals to which power is distributed proceeds to the switch 9 as it is, and the other one passes through the phase shifter 8 and is input to the switch 9 while having a phase difference of 90 ° with respect to the previous signal. The switch 9 is a switch for selecting two response signals. The switch 9 selects either an original signal or a response signal for arbitrary control, and inputs the response signal to the mixer 10. Synchronous detection is realized by using a part of the power of the transmission amplifier 4 for the LO signal of the mixer 10. The response signal obtained by the mixer 10 is subjected to processing such as amplification by removing unnecessary wave components by the reception unit 11 and processed as a response data signal by the control unit 2. The above is a series of signal flows in the interrogator of the present invention.

  Next, an operation for obtaining the effect of phase diversity will be described. When the interrogator 30 of the configuration example 1 transmits a certain command “question signal 1”, the responder 20 transmits “response signal 1” which is a response corresponding to “question signal 1”. In this case, the interrogator 30 of the configuration example 1 is in a receiving state for receiving a response signal to the “question signal 1”, and is in a state where it cannot transmit the next question signal. The interrogator 30 of the configuration example 1 in the reception state receives the “response signal 1” by the antenna 6, passes through the circulator 5 and the distributor 7, passes through the phase shifter 8, and “phase difference 90 ° signal”. A “signal with a phase difference of 0 °” does not pass through the shifter 8. When the switch 9 selects the path side of the phase shifter 8, the “response signal 1” “signal having a phase difference of 90 °” is input to the mixer 10, and this signal is acquired as data.

  Further, there are cases where the acquired data cannot be detected due to a phase shift caused by the distance relationship with the responder 20. In this case, the interrogator 30 of the configuration example 1 transmits the “question signal 1” again with the switch 9 not passing through the path of the phase shifter 8. The responder 20 transmits the response “response signal 1” corresponding to the “question signal 1” again. Similarly, the interrogator 30 in the reception state receives the “response signal 1” by the antenna 6, passes through the circulator 5 and the distributor 7, passes through the phase shifter 8, and the “phase difference 90 ° signal”. A “phase difference 0 ° signal” that does not pass 8 is obtained. In this case, since the switch 9 of the interrogator 30 of the configuration example 1 selects the path side that does not pass through the phase shifter 8, the “response signal 1” “signal having a phase difference of 0 °” is input to the mixer 10. The signal is acquired as data.

  That is, the interrogator 30 of the configuration example 1 of the present invention switches the response to one “question signal 1” by switching the switch 9, so that the “response signal 1” signal of 90 ° phase difference ”and the“ response signal ” Since both “1” and “signal having a phase difference of 0 °” can be taken in time series, the effect of phase diversity can be obtained.

  Note that the interrogator 30 of the configuration example 1 of the present invention can reduce the number of distributors, mixers, and receivers that are the receiving circuit of the interrogator of the conventional example shown in FIG. The number of parts can be reduced by about 45%. As a result, downsizing is realized.

  Further, since the interrogator 30 of the configuration example 1 of the present invention can reduce the number of the receiving circuit systems to one system for miniaturization, the power of the receiving circuit can be reduced to about ½. As a result, low power consumption is realized.

  As shown in FIG. 2, the interrogator 31 (configuration example 2) of the mobile object identification apparatus according to the best mode for carrying out the present invention includes a synthesizer 1, a control unit 2, a modulator 3, a transmission amplifier 4, and a circulator. 5, a transmission / reception antenna 6, a distributor 7 for distributing received signal power, a phase shifter 8 for shifting the phase by 90 °, a switch 9 for switching the received signal, a mixer 10, and a receiving unit 11. The main components are the same as those in Configuration Example 1. The responder 20 communicates with the interrogator via the antenna 21.

  The interrogation operation of the interrogator 31 (configuration example 2) of the mobile object identification device according to the best mode for carrying out the present invention is as follows. As shown in FIG. 2, the signal of the carrier wave generated by the synthesizer 1 becomes a modulation signal according to the data signal sent from the control unit 2 by the modulator 3. This modulated signal is amplified by the transmission amplifier 4, passes through the circulator 5 and the antenna 6, and is radiated to the space. The modulated signal radiated to the space is received by the antenna 21 of the responder 20. The responder performs predetermined processing and sends a response signal from the antenna 21.

  The interrogator 31 of the configuration example 2 receives the response signal from the responder 20 by the antenna 6 and inputs it to the mixer 10. The LO signal to the mixer 10 uses a part of the power of the transmission amplifier 4, is further distributed by the distributor 7, and then is connected to the switch 9 as it is and the previous path via the phase shifter 8. It is divided into a path connecting to the switch 9 with a phase difference of 90 °. The switch 9 is a switch for selecting two LO signals, and selects either an arbitrary control source or an LO signal and inputs the LO signal to the mixer 10.

  That is, in the interrogator 30 of the configuration example 1 of the present invention, the response signal has a phase difference, whereas in the interrogator 31 of the configuration example 2 of the present invention, the LO signal has a phase difference. . By switching the path of this LO signal with the switch 9, the phase diversity effect is obtained as in the first configuration example.

  Next, an operation for obtaining the effect of phase diversity in the interrogator 31 of the configuration example 2 of the present invention will be described. As shown in FIG. 2, when the interrogator 31 of the configuration example 2 transmits “question signal 1” that is a certain command, the responder 20 transmits “response signal 1” that is a response corresponding to “question signal 1”. Send it out. In this case, the interrogator 31 is in a receiving state where it can receive a response signal to the “question signal 1”, and is in a state where it cannot transmit the next interrogating signal. The interrogator 31 in the reception state receives the “response signal 1” by the antenna 6, and inputs it to the mixer 10 through the circulator 5. When the switch 9 selects the path side of the phase shifter 8, the “response signal 1” and the “LO signal having a phase difference of 90 °” are input to the mixer 10. Is obtained as data.

  In this case, there is a case where the acquired data cannot be detected due to a phase shift caused by a distance relationship with the responder 20. In this case, the switch 9 is set so as not to pass the path of the phase shifter 8 and the “question signal 1” is transmitted again. The responder 20 transmits the response “response signal 1” corresponding to the “question signal 1” again. Similarly, the interrogator 31 in the reception state receives the “response signal 1” by the antenna 6, passes through the circulator 5, and is input to the mixer 10. On the other hand, since the “LO signal having a phase difference of 0 °” that does not pass through the phase shifter 8 is selected as the LO signal, the “response signal 1” and the “LO signal having a phase difference of 0 °” are input to the mixer 10. Data is acquired. That is, the interrogator 31 of the configuration example 2 of the present invention switches the response to one “question signal 1” with the switch 9, and the “response signal 1” “LO signal with a phase difference of 90 °” and the “response signal 1”. The “LO signal with a phase difference of 0 °” is captured in time series to obtain the effect of phase diversity.

  The interrogator 31 of the configuration example 2 of the present invention can reduce the number of distributors, mixers, and receivers, which are the reception circuits of the conventional interrogator shown in FIG. The number of parts can be reduced by about 45%. As a result, downsizing is realized.

  Further, since the interrogator 31 of the configuration example 2 of the present invention can reduce the number of the receiving circuit systems to one for miniaturization, the power of the receiving circuit can be reduced to about ½. As a result, low power consumption is realized.

  Even in the configuration examples shown above, the means of phase shift is not limited to this example, and it can be replaced by using a transmission line length instead of a phase shifter or by using a 90 ° hybrid coupler as a distributor. it is obvious. In the phase diversity operation, the diversity effect is obtained by performing transmission and reception twice. For one transmission, for example, “question signal 1”, the responder has “response signal 1”, “response” The interrogator can change the switch and receive it twice by switching the switch so that the same data such as the signal 1 ′ ”responds twice.

  As described above, according to the present invention, phase diversity can be realized with a small-scale circuit configuration as compared with a circuit used in a conventionally used phase diversity method. As a result, it is possible to provide a small-sized mobile object identification device called a handy type equipped with a power-saving interrogator.

The block diagram which shows the structural example 1 of the interrogator of the mobile body identification device which concerns on the best form for implementing this invention. The block diagram which shows the structural example 2 of the interrogator of the mobile body identification device which concerns on the best form for implementing this invention. The block diagram which shows the structural example of the mobile body identification device of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Synthesizer 2 Control part 3 Modulator 4 Transmission amplifier 5 Circulator 6 Antenna 7, 7a, 7b Divider 8 Phase shifter 9 Switch 10, 10a, 10b Mixer 11, 11a, 11b Receiving part 20 Responder 21 Antenna (responder)
30 Interrogator (of the present invention) (Configuration Example 1)
31 Interrogator (Configuration Example 2)
32 Interrogator (conventional example)

Claims (2)

  A mobile unit comprising an interrogator that performs detection of a received signal using a synchronous detection method, and a transponder that receives the interrogation wave from the interrogator, performs specific modulation on the interrogation wave, and transmits it as a response wave In the identification device, the interrogator includes means for giving a received signal a phase difference of 90 ° and a switch for selecting one of the two signals having the phase difference between each other, and switching the switch A moving body identifying apparatus characterized in that phase diversity is realized by switching the phase of the received signal.   The interrogator is equipped with a mixer that demodulates the received signal, and receives the interrogation wave from the interrogator, performs specific modulation on the interrogation wave, and produces a response wave In a mobile unit identification apparatus comprising a responder for transmission, means for giving a 90 ° phase difference to a local signal (LO signal) of the mixer and two local signals (LO) having the phase difference between each other A moving object identification device characterized by comprising a switch for selecting one of (signal) and switching the switch to switch the local signal (LO signal) to realize phase diversity.

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